UCF STIG Viewer Logo

The OL 8 SSH server must be configured to use strong entropy.


Finding ID Version Rule ID IA Controls Severity
V-248563 OL08-00-010292 SV-248563r779255_rule Low
The most important characteristic of a random number generator is its randomness, namely its ability to deliver random numbers that are impossible to predict. Entropy in computer security is associated with the unpredictability of a source of randomness. The random source with high entropy tends to achieve a uniform distribution of random values. Random number generators are one of the most important building blocks of cryptosystems. The SSH implementation in OL 8 uses the OPENSSL library, which does not use high-entropy sources by default. By using the SSH_USE_STRONG_RNG environment variable, the OPENSSL random generator is reseeded from "/dev/random". This setting is not recommended on computers without the hardware random generator because insufficient entropy causes the connection to be blocked until enough entropy is available.
Oracle Linux 8 Security Technical Implementation Guide 2022-12-06


Check Text ( C-51997r779253_chk )
Verify the operating system SSH server uses strong entropy with the following command:

$ sudo grep -i ssh_use_strong_rng /etc/sysconfig/sshd


If the "SSH_USE_STRONG_RNG" line does not equal "32" or is commented out or missing, this is a finding.
Fix Text (F-51951r779254_fix)
Configure the operating system SSH server to use strong entropy.

Add or modify the following line in the "/etc/sysconfig/sshd" file.


The SSH service must be restarted for changes to take effect.